Automatic Control System for Forklift Truck Service Braking

Abstract

The present invention discloses an automatic control system for the driving brake of a forklift. The main design concept of the present invention lies in using an independent pump station integrating two pressure switches, an accumulator, a brake valve, and a brake to form a set of concise and functionally intact driving brake systems, abandoning existing devices such as fluid filling valves, making the pipeline of the whole system simple and the structure compact. This not only facilitates assembly, maintenance, and repair, but also can significantly reduce the system cost. Specifically, mainly through the additional two-way pressure feedback signals, precise control of the motor start and stop can be achieved as required, reducing the hydraulic power loss of the system, lowering energy consumption, thereby improving the system efficiency, and also facilitating the implementation and application by those skilled in the art.

Description

Technical Field

[0001] The present invention relates to the technical field of forklifts, and in particular to an automatic control system for the driving brake of a forklift. Background Art

[0002] The driving brake systems configured for existing large-tonnage forklifts usually use hydraulic oil as the braking medium. To ensure the reliability of braking, in addition to brakes and brake valves, many other hydraulic components such as dedicated pumps, fluid filling valves, accumulators, etc. are also configured in the driving brake system. When the vehicle starts, the dedicated brake pump starts to work and does not stop until the vehicle stops and the power is cut off. Such a driving brake system has many hydraulic components, poor assembly and maintenance performance, a complex system with high costs, and high system energy consumption. Summary of the Invention

[0003] In view of the above, the present invention aims to provide an automatic control system for the driving brake of a forklift to solve the problems of the existing driving brake system such as complex structure, difficult arrangement of components, high costs, and high system energy consumption.

[0004] The technical solution adopted by the present invention is as follows:

[0005] The present invention provides an automatic control system for the driving brake of a forklift, which includes: a power unit, an accumulator, a brake valve, a first brake, and a second brake;

[0006] Wherein, the power unit is integrated with a fuel tank, a motor, a gear pump, a one-way valve, a lower limit pressure switch, an upper limit pressure switch, and an electromagnetic directional valve;

[0007] The lower limit pressure switch and the upper limit pressure switch are communicated with the front-section pipeline of the working oil port of the power unit through an internal oil passage, and the lower limit pressure switch is electrically signal-associated with the motor, and the upper limit pressure switch is electrically signal-associated with the motor and the electromagnetic directional valve;

[0008] The suction port of the gear pump is communicated with the fuel tank, and the oil outlet of the gear pump is connected to at least two oil circuits: the first oil circuit is connected to the oil inlet of the electromagnetic directional valve, the oil outlet of the electromagnetic directional valve is communicated with the internal oil return passage, and the oil return passage is communicated with the fuel tank; the second oil circuit is connected to the oil inlet of the one-way valve, and the oil outlet of the one-way valve is respectively connected to three oil circuits:

[0009] The third oil circuit is connected to the lower limit pressure switch, the fourth oil circuit is connected to the upper limit pressure switch, and the fifth oil circuit is connected to the working oil port of the power unit;

[0010] The working oil ports of the power unit are respectively communicated with the working oil ports of the accumulator and the oil inlet of the brake valve. The working oil ports of the brake valve are respectively communicated with the oil ports of the first brake and the second brake. The oil return port of the brake valve is communicated with the internal oil return passage through the oil return port of the power unit.

[0011] In at least one possible implementation, the power unit is also integrated with an oil suction filter element, and the oil suction port of the gear pump is communicated with the fuel tank through the oil suction filter element.

[0012] In at least one possible implementation, the power unit is also integrated with a relief valve, and the oil outlet of the gear pump is communicated with the internal oil return passage through the relief valve.

[0013] In at least one possible implementation, the control system further includes: a first three-way pipe, and the working oil port of the power unit is respectively communicated with the working oil port of the accumulator and the oil inlet of the brake valve through the first three-way pipe.

[0014] In at least one possible implementation, the control system further includes: a second three-way pipe, and the working oil port of the brake valve is respectively communicated with the oil ports of the first brake and the second brake through the second three-way pipe.

[0015] In at least one possible implementation, the electromagnetic directional valve adopts a two-position two-way electromagnetic directional valve.

[0016] In at least one possible implementation, the brake valve adopts a three-position three-way directional valve.

[0017] Compared with the prior art, the main design concept of the present invention is to use an independent pump station integrating two pressure switches, an accumulator, a brake valve, and a brake to form a set of streamlined and functionally lossless vehicle braking system, and discard existing devices such as a filling valve, etc., making the whole system pipeline simple and the structure compact. It is not only convenient for assembly, maintenance and repair, but also can significantly reduce the system cost. Specifically, mainly through the additional two-way pressure feedback signals, the accurate control of the motor start and stop can be realized as required, reducing the hydraulic power loss of the system, lowering the energy consumption, thereby improving the system efficiency, and also facilitating the implementation and application by those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described below in conjunction with the drawings, where:

[0019] Figure 1 is a schematic diagram of the automatic control system for the vehicle braking of the forklift provided by the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present invention and should not be construed as limiting the present invention.

[0021] An embodiment of an automatic control system for the service brake of a forklift is proposed by the present invention. Specifically, as Figure 1 shown, it includes:

[0022] Components such as a power unit 1, an accumulator 2, a brake valve 3, a first brake 4, and a second brake 5 connected by pipelines.

[0023] Specifically, the power unit 1 integrates a fuel tank 8, an oil suction filter element 9 (preferably), a motor 10, a gear pump 11, an overflow valve 12 (preferably), a check valve 13, a lower limit pressure switch 14, an upper limit pressure switch 15, and an electromagnetic directional control valve 16. Each component is connected through an oil passage and pipe fittings inside the power unit 1.

[0024] Among them, the lower limit pressure switch 14 and the upper limit pressure switch 15 are communicated with the front-section pipeline of the working oil port P of the power unit 1 through an internal oil passage K (here, the front and back are relative concepts with respect to the oil flow direction). The lower limit pressure switch 14 is electrically signal-associated with the motor 10, and the upper limit pressure switch 15 is electrically signal-associated with the motor 10 and the electromagnetic directional control valve 16;

[0025] The oil suction port of the gear pump 11 can be communicated with the fuel tank 8 through the oil suction filter element 9, and the oil outlet of the gear pump 11 is connected to at least two oil circuits:

[0026] The first oil circuit is connected to the oil inlet X of the electromagnetic directional control valve 16. The oil outlet Xt of the electromagnetic directional control valve 16 communicates with the internal oil return passage H, and the oil return passage H communicates with the fuel tank 8. The second oil circuit is connected to the oil inlet of the check valve 13, and the oil outlet of the check valve 13 is respectively connected to three oil circuits:

[0027] The third oil circuit is connected to the lower limit pressure switch 14, the fourth oil circuit is connected to the upper limit pressure switch 15 (these two circuits can correspond to the aforementioned internal oil passage K), and the fifth oil circuit is connected to the working oil port P of the power unit 1;

[0028] The working oil port P of the power unit 1 can be connected to the working oil port P2 of the accumulator 2 and the oil inlet P1 of the brake valve 3 respectively through a first three-way pipe 7 (preferably), and the working oil port Br of the brake valve 3 can be connected to the oil ports of the first brake 4 and the second brake 5 respectively through a second three-way pipe 6 (preferably), and the return oil port Bt of the brake valve 3 is connected to the internal return oil channel H through the return oil port T of the power unit 1.

[0029] Specifically, the electromagnetic reversing valve 16 preferably adopts a two-position two-way electromagnetic reversing valve, so that its working mode can be referred to as follows: when the electromagnetic reversing valve 16 is in the lower position, the oil inlet X and the oil return port Xt are not connected; when the electromagnetic reversing valve 16 is energized and is in the upper position, the oil inlet X and the oil return port Xt are connected, and the oil at the oil outlet of the gear pump 11 enters the oil return channel H through the oil inlet X and the oil outlet Xt and flows back to the oil tank 8.

[0030] Specifically, the brake valve 3 preferably adopts a three-position three-way reversing valve, so that its working mode can be referred to as follows: when the brake valve 3 is in the lower position, its working oil port Br is connected to the return oil port Bt, and the oil in the first brake 4 and the second brake 5 can pass through the oil ports Bt and Br of the brake valve 3 and the return oil port T of the power unit 1 into the return oil channel H and flow back to the oil tank 8; when the brake valve 3 is in the middle position, the aforementioned working oil ports P1, Bt, and Br are not connected to each other; when the brake valve 3 is in the upper position, its oil inlet P1 is connected to the working oil port Br.

[0031] In addition, for some of the aforementioned embodiments that use the overflow valve 12 , the oil outlet of the gear pump 11 can also be connected to the internal oil return channel H through the overflow valve 12 .

[0032] Based on the above embodiments, the working mode of the present invention is schematically introduced as follows:

[0033] The setting pressure of the lower limit pressure switch 14 can be P 下 , the setting pressure of the upper limit pressure switch 15 can be P 上 When the forklift key switch is closed and the vehicle is powered on, the service brake pedal can be left unoperated, and the brake valve 3 is in the lower position. In this system, the oil pressure in the accumulator 2 and the oil channel K inside the power unit 1 will be in the following two situations:

[0034] In the first case, the accumulator pressure is lower than the set pressure P of the lower limit pressure switch 14. 下 ; In the second case, the accumulator pressure is higher than the set pressure P of the lower limit pressure switch 14 下 , but it is lower than the set pressure of the upper pressure switch 15, which is P 上 .

[0035] When the accumulator pressure is lower than P 下When the lower limit pressure switch 14 triggers a signal, the motor 10 receives this signal and starts to operate, driving the gear pump 11. The oil in the fuel tank 8 passes through (the oil suction filter element 9), the gear pump 11, the one-way valve 12, and is divided into three paths to be respectively connected to the working oil ports P of the lower limit pressure switch 14, the upper limit pressure switch 15, and the power unit 1. The oil at the working oil port P passes through the first three-way pipe 7 to be connected to the working oil port P2 of the accumulator 2 and the oil inlet P1 of the brake valve 3. At this time, the oil inlet P1 of the brake valve 3 is not connected to the working oil port Br, and the oil at the working oil port P can only enter the accumulator 2 to fill the accumulator 2 with liquid. The oil pressure in the accumulator 2 and the internal oil passage K of the power unit 1 is the same and rises synchronously; when the oil pressure in the internal oil passage K reaches P 上 When the upper limit pressure switch 15 triggers a signal, the motor 10 and the electromagnetic directional valve 16 can receive this signal simultaneously. The motor 10 receives the signal and stops operating, and the gear pump 11 stops filling the accumulator 2 with liquid. The electromagnetic directional valve 16 is energized and commutated, and its oil inlet X is connected to the oil return port Xt to realize system unloading.

[0036] Particularly more preferably, when a fault occurs in the system and the motor 10 cannot stop rotating in time, the electromagnetic directional valve 16 is energized and commutated to unload the system to prevent system overload; and when a further fault occurs in the system and the motor 10 cannot stop rotating in time and the electromagnetic directional valve 16 cannot normally unload the system, when the accumulator pressure continuously rises to the set pressure of the overflow valve 12, the oil inlet and outlet of the overflow valve are conducted, and the oil at the outlet of the gear pump 11 flows back to the fuel tank 8 through the overflow valve 12, and the accumulator pressure no longer continues to rise, protecting the system.

[0037] When the accumulator pressure is higher than the set pressure P of the lower limit pressure switch 14 下 , but lower than the set pressure P of the upper limit pressure switch 15 上 When this happens, neither of the two pressure switches will provide a trigger signal, and the motor 10 will not start operating. The accumulator 2 is in a pressure-holding state, and the pressure it stores is sufficient to meet the pressure requirements for vehicle braking.

[0038] When the accumulator 2 maintains pressure, there is no braking effect when the brake valve 3 is in the middle position when the brake pedal is depressed. When the brake valve 3 is in the upper position, the oil inlet P1 of the brake valve 3 is connected to the working oil port Br. The high-pressure oil in the accumulator 2 enters the brake chambers of the first brake 4 and the second brake 5 simultaneously through two paths after passing through the brake valve 3 and the second three-way pipe 6, achieving braking; at the same time, the pressure in the accumulator 2 decreases. When the brake pedal is released, the brake valve 3 returns to the lower position, and the working oil port Br is connected to the oil return port Bt. The oil in the brake chambers of the first brake 4 and the second brake 5 enters the oil return passage H inside the power unit 1 through the second three-way pipe 6, the brake valve 3, and the oil return port T of the power unit 1, and flows back to the fuel tank, releasing the brake. After repeatedly stepping on and releasing the brake pedal, the oil in the accumulator 2 decreases and the pressure drops, and the pressures detected by the lower limit pressure switch 14 and the upper limit pressure switch 15 decrease synchronously. When the pressure drops to the set pressure P of the lower limit pressure switch 14 下 , the trigger signal motor 10 receives the signal and starts to drive the gear pump 11 to work, filling the accumulator 2 with liquid; when the accumulator pressure rises to the set pressure P of the upper limit pressure switch 15 上 , the motor 10 stops rotating and at the same time the electromagnetic directional valve 16 is energized and commutated to the upper position, and the system unloads.

[0039] In this way, the system can realize actions such as automatic liquid filling, stopping liquid filling, and system unloading according to actual needs, meeting the braking requirements of large-tonnage forklifts.

[0040] In summary, the main design concept of the present invention is to use an independent pump station integrating two pressure switches, an accumulator, a brake valve, and a brake to form a set of concise and functionally intact service brake system, abandoning existing devices such as liquid filling valves, making the entire system pipeline simple and the structure compact. It is not only convenient for assembly, maintenance, and overhaul, but also can significantly reduce the system cost. Specifically, mainly through the additional two-way pressure feedback signals, the accurate control of the motor start and stop can be realized as needed, reducing the hydraulic power loss of the system, reducing energy consumption, thereby improving the system efficiency, and also facilitating the implementation and application by those skilled in the art.

[0041] In the embodiments of the present invention, if there are any expressions referring to directions, they are relative concepts based on the embodiments. In addition, "at least one" means one or more, and "a plurality of" means two or more. "And / or" describes the relationship between associated objects and indicates that there can be three relationships. For example, A and / or B can represent the cases where A exists alone, A and B exist simultaneously, and B exists alone. Here, A and B can be singular or plural. The character " / " generally indicates an "or" relationship between the associated objects before and after. "At least one of the following" and its similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, and c can represent: a, b, c, a and b, a and c, b and c, or a and b and c, where a, b, and c can be single or multiple.

[0042] The structure, features, and effects of the present invention have been described in detail based on the embodiments shown in the drawings above. However, the above are only the preferred embodiments of the present invention. It should be noted that for the technical features involved in the above embodiments and their preferred modes, those skilled in the art can, without departing from or changing the design concept and technical effects of the present invention, reasonably combine and match them into various equivalent solutions. Therefore, the scope of the present invention is not limited by the drawings. Any changes made according to the concept of the present invention or equivalent embodiments modified to equivalent changes that still do not exceed the spirit covered by the description and the drawings should be within the protection scope of the present invention.

Claims

1. An automatic control system for the driving brake of a forklift, characterized in that, Comprising: A power unit, an accumulator, a brake valve, a first brake, and a second brake; Wherein, the power unit is integrated with a fuel tank, a motor, a gear pump, a check valve, a lower pressure switch, an upper pressure switch, and an electromagnetic directional control valve; The lower pressure switch and the upper pressure switch are communicated with the front pipeline of the working oil port of the power unit through an internal oil passage, and the lower pressure switch is electrically connected to the motor, and the upper pressure switch is electrically connected to the motor and the electromagnetic directional control valve; The suction port of the gear pump is communicated with the fuel tank, and the outlet port of the gear pump is connected to at least two oil circuits: the first oil circuit is connected to the inlet port of the electromagnetic directional control valve, the outlet port of the electromagnetic directional control valve is communicated with the internal oil return passage, and the oil return passage is communicated with the fuel tank; the second oil circuit is connected to the inlet port of the check valve, and the outlet port of the check valve is respectively connected to three oil circuits: The third oil circuit is connected to the lower pressure switch, the fourth oil circuit is connected to the upper pressure switch, and the fifth oil circuit is connected to the working oil port of the power unit; The working oil port of the power unit is respectively communicated with the working oil port of the accumulator and the inlet port of the brake valve, the working oil port of the brake valve is respectively communicated with the oil ports of the first brake and the second brake, and the oil return port of the brake valve is communicated with the internal oil return passage through the oil return port of the power unit.

2. The automatic control system for the driving brake of a forklift according to claim 1, characterized in that, The power unit is further integrated with an oil suction filter element, and the suction port of the gear pump is communicated with the fuel tank through the oil suction filter element.

3. The automatic control system for the driving brake of a forklift according to claim 1, characterized in that, The power unit is further integrated with a relief valve, and the outlet port of the gear pump is communicated with the internal oil return passage through the relief valve.

4. The automatic control system for the driving brake of a forklift according to claim 1, characterized in that, The control system further includes: a first three-way pipe, and the working oil port of the power unit is respectively communicated with the working oil port of the accumulator and the inlet port of the brake valve through the first three-way pipe.

5. The automatic control system for the driving brake of a forklift according to claim 1, characterized in that, The control system further includes: a second three-way pipe, and the working oil port of the brake valve is respectively communicated with the oil ports of the first brake and the second brake through the second three-way pipe.

6. The automatic control system for the driving brake of a forklift according to any one of claims 1 to 5, characterized in that, The electromagnetic directional control valve adopts a two-position two-way electromagnetic directional control valve.

7. The automatic control system for the driving brake of a forklift according to any one of claims 1 to 5, characterized in that, The brake valve adopts a three-position three-way directional control valve.

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